Further Improve Kafka Test Run Time

Configurable `timeoutBuffer`.

spring-integration-kafka/src/main/java/org/springframework/integration/kafka/outbound/KafkaProducerMessageHandler.java

@@ -105,7 +105,7 @@ public class KafkaProducerMessageHandler<K, V> extends AbstractReplyProducingMes
 	/**
 	 * Buffer added to ensure our timeout is longer than Kafka's.
 	 */
-	private static final int TIMEOUT_BUFFER = 5000;
+	private static final int DEFAULT_TIMEOUT_BUFFER = 5000;
 
 	private final Map<String, Set<Integer>> replyTopicsAndPartitions = new HashMap<>();
 
@@ -162,6 +162,8 @@ public class KafkaProducerMessageHandler<K, V> extends AbstractReplyProducingMes
 			(message, topic, partition, timestamp, key, value, headers) ->
 					new ProducerRecord<>(topic, partition, timestamp, key, value, headers);
 
+	private int timeoutBuffer = DEFAULT_TIMEOUT_BUFFER;
+
 	private volatile byte[] singleReplyTopic;
 
 	public KafkaProducerMessageHandler(final KafkaTemplate<K, V> kafkaTemplate) {
@@ -188,7 +190,7 @@ public class KafkaProducerMessageHandler<K, V> extends AbstractReplyProducingMes
 		determineSendTimeout();
 		this.deliveryTimeoutMsProperty =
 				this.sendTimeoutExpression.getValue(Long.class) // NOSONAR - never null after determineSendTimeout()
-						- TIMEOUT_BUFFER;
+						- this.timeoutBuffer;
 	}
 
 	private void determineSendTimeout() {
@@ -198,13 +200,13 @@ public class KafkaProducerMessageHandler<K, V> extends AbstractReplyProducingMes
 			dt = ProducerConfig.configDef().defaultValues().get(ProducerConfig.DELIVERY_TIMEOUT_MS_CONFIG);
 		}
 		if (dt instanceof Long) {
-			setSendTimeout(((Long) dt) + TIMEOUT_BUFFER);
+			setSendTimeout(((Long) dt) + this.timeoutBuffer);
 		}
 		else if (dt instanceof Integer) {
-			setSendTimeout(Long.valueOf((Integer) dt) + TIMEOUT_BUFFER);
+			setSendTimeout(Long.valueOf((Integer) dt) + this.timeoutBuffer);
 		}
 		else if (dt instanceof String) {
-			setSendTimeout(Long.parseLong((String) dt) + TIMEOUT_BUFFER);
+			setSendTimeout(Long.parseLong((String) dt) + this.timeoutBuffer);
 		}
 	}
 
@@ -290,10 +292,12 @@ public class KafkaProducerMessageHandler<K, V> extends AbstractReplyProducingMes
 	 * Specify a SpEL expression to evaluate a timeout in milliseconds for how long this
 	 * {@link KafkaProducerMessageHandler} should wait wait for send operation results.
 	 * Defaults to the kafka {@code delivery.timeout.ms} property + 5 seconds. The timeout
-	 * is applied only in {@link #sync} mode.
+	 * is applied only in {@link #sync} mode. If this expression yields a result that is
+	 * less than that value, the higher value is used.
 	 * @param sendTimeoutExpression the {@link Expression} for timeout to wait for result
 	 * for a send operation.
 	 * @since 2.1.1
+	 * @see #setTimeoutBuffer(int)
 	 */
 	public void setSendTimeoutExpression(Expression sendTimeoutExpression) {
 		Assert.notNull(sendTimeoutExpression, "'sendTimeoutExpression' must not be null");
@@ -404,6 +408,18 @@ public class KafkaProducerMessageHandler<K, V> extends AbstractReplyProducingMes
 		this.producerRecordCreator = producerRecordCreator;
 	}
 
+	/**
+	 * Set a buffer, in milliseconds, added to the configured {@code delivery.timeout.ms}
+	 * to determine the minimum time to wait for the send future completion when
+	 * {@link #setSync(boolean) sync} is true.
+	 * @param timeoutBuffer the buffer.
+	 * @since 5.4
+	 * @see #setSendTimeoutExpression(Expression)
+	 */
+	public void setTimeoutBuffer(int timeoutBuffer) {
+		this.timeoutBuffer = timeoutBuffer;
+	}
+
 	@Override
 	public String getComponentType() {
 		return this.isGateway ? "kafka:outbound-gateway" : "kafka:outbound-channel-adapter";
@@ -680,10 +696,10 @@ public class KafkaProducerMessageHandler<K, V> extends AbstractReplyProducingMes
 			Long sendTimeout = this.sendTimeoutExpression.getValue(this.evaluationContext, message, Long.class);
 			if (sendTimeout != null && sendTimeout <= this.deliveryTimeoutMsProperty) {
 				this.logger.debug("'sendTimeout' increased to "
-						+ (this.deliveryTimeoutMsProperty + TIMEOUT_BUFFER)
+						+ (this.deliveryTimeoutMsProperty + this.timeoutBuffer)
 						+ "ms; it must be greater than the 'delivery.timeout.ms' Kafka producer "
 						+ "property to avoid false failures");
-				sendTimeout = this.deliveryTimeoutMsProperty + TIMEOUT_BUFFER;
+				sendTimeout = this.deliveryTimeoutMsProperty + this.timeoutBuffer;
 			}
 			if (sendTimeout == null || sendTimeout < 0) {
 				future.get();

spring-integration-kafka/src/test/java/org/springframework/integration/kafka/config/xml/KafkaOutboundAdapterParserTests.java

@@ -122,6 +122,7 @@ class KafkaOutboundAdapterParserTests {
 
 		handler.setSync(true);
 		handler.setSendTimeout(10);
+		handler.setTimeoutBuffer(200);
 		handler.setTopicExpression(new LiteralExpression("foo"));
 
 		Executors.newSingleThreadExecutor()